A standard handle assembly as described in German patent 1,675,417 issued Jan. 8, 1976 to E. Winterhoff fits on a valve having a stem rotatable about an axis. The assembly comprises a noncircular axially extending formation centered on the axis and fixed on the stem, a retaining element fixed to the stem and formed centered on the axis with an array of axially extending and radially deflectable tongues axially offset from the stem formation and having radially outwardly directed bumps of a predetermined diameter, and a handle having a hub formed with a hole fittable axially over the retaining element and formed inside the hole with a handle formation complementary to and fittable axially with the stem formation and with a radially inwardly open groove. The stem is a actually formed by a splined metal shaft carrying a plastic cup itself having the noncircular coupling formation. The handle fits with its hole over the element with the formations interengaged and the bumps in the groove. Thus the handle is simply snapped axially onto the stem and is retained in place by the bumps pressed radially elastically outward into the groove.
Such a system has the advantage of extreme simplicity, while still solidly angularly coupling the handle via the interfitting formations to the stem. The problem exists, however, that an axial pull on the handle can tug it right off the stem. Thus the handle can be easily pulled off the valve intentionally or accidentally.